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cpuset: Convert callback_lock to raw_spinlock_t 

The two commits below add up to a cpuset might_sleep() splat for RT:

8447a0fee9 cpuset: convert callback_mutex to a spinlock
344736f29b cpuset: simplify cpuset_node_allowed API

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:995
in_atomic(): 0, irqs_disabled(): 1, pid: 11718, name: cset
CPU: 135 PID: 11718 Comm: cset Tainted: G            E   4.10.0-rt1-rt #4
Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
Call Trace:
 ? dump_stack+0x5c/0x81
 ? ___might_sleep+0xf4/0x170
 ? rt_spin_lock+0x1c/0x50
 ? __cpuset_node_allowed+0x66/0xc0
 ? ___slab_alloc+0x390/0x570 <disables IRQs>
 ? anon_vma_fork+0x8f/0x140
 ? copy_page_range+0x6cf/0xb00
 ? anon_vma_fork+0x8f/0x140
 ? __slab_alloc.isra.74+0x5a/0x81
 ? anon_vma_fork+0x8f/0x140
 ? kmem_cache_alloc+0x1b5/0x1f0
 ? anon_vma_fork+0x8f/0x140
 ? copy_process.part.35+0x1670/0x1ee0
 ? _do_fork+0xdd/0x3f0
 ? _do_fork+0xdd/0x3f0
 ? do_syscall_64+0x61/0x170
 ? entry_SYSCALL64_slow_path+0x25/0x25

The later ensured that a NUMA box WILL take callback_lock in atomic
context by removing the allocator and reclaim path __GFP_HARDWALL
usage which prevented such contexts from taking callback_mutex.

One option would be to reinstate __GFP_HARDWALL protections for
RT, however, as the 8447a0fee9 changelog states:

The callback_mutex is only used to synchronize reads/updates of cpusets'
flags and cpu/node masks. These operations should always proceed fast so
there's no reason why we can't use a spinlock instead of the mutex.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
This commit is contained in:
Mike Galbraith 2017-01-08 09:32:25 +01:00 committed by Alibek Omarov
parent 085e434453
commit e776981391
1 changed files with 35 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
kernel/cgroup/cpuset.c
View File

@ -345,7 +345,7 @@ void cpuset_read_unlock(void)
percpu_up_read(&cpuset_rwsem);
}
static DEFINE_SPINLOCK(callback_lock);
static DEFINE_RAW_SPINLOCK(callback_lock);
static struct workqueue_struct *cpuset_migrate_mm_wq;
@ -1278,7 +1278,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd,
* Newly added CPUs will be removed from effective_cpus and
* newly deleted ones will be added back to effective_cpus.
*/
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
if (adding) {
cpumask_or(parent->subparts_cpus,
parent->subparts_cpus, tmp->addmask);
@ -1297,7 +1297,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd,
}
parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus);
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
return cmd == partcmd_update;
}
@ -1402,7 +1402,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp)
continue;
rcu_read_unlock();
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cpumask_copy(cp->effective_cpus, tmp->new_cpus);
if (cp->nr_subparts_cpus &&
@ -1433,7 +1433,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp)
= cpumask_weight(cp->subparts_cpus);
}
}
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
WARN_ON(!is_in_v2_mode() &&
!cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
@ -1561,7 +1561,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
return -EINVAL;
}
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
/*
@ -1571,7 +1571,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
cpumask_and(cs->subparts_cpus, cs->subparts_cpus, cs->cpus_allowed);
cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
}
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
update_cpumasks_hier(cs, &tmp);
@ -1765,9 +1765,9 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
continue;
rcu_read_unlock();
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cp->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
WARN_ON(!is_in_v2_mode() &&
!nodes_equal(cp->mems_allowed, cp->effective_mems));
@ -1835,9 +1835,9 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
if (retval < 0)
goto done;
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cs->mems_allowed = trialcs->mems_allowed;
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
/* use trialcs->mems_allowed as a temp variable */
update_nodemasks_hier(cs, &trialcs->mems_allowed);
@ -1928,9 +1928,9 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
|| (is_spread_page(cs) != is_spread_page(trialcs)));
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cs->flags = trialcs->flags;
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
rebuild_sched_domains_locked();
@ -2441,7 +2441,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
cpuset_filetype_t type = seq_cft(sf)->private;
int ret = 0;
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
switch (type) {
case FILE_CPULIST:
@ -2463,7 +2463,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
ret = -EINVAL;
}
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
return ret;
}
@ -2776,14 +2776,14 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
cpuset_inc();
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
if (is_in_v2_mode()) {
cpumask_copy(cs->effective_cpus, parent->effective_cpus);
cs->effective_mems = parent->effective_mems;
cs->use_parent_ecpus = true;
parent->child_ecpus_count++;
}
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
goto out_unlock;
@ -2810,12 +2810,12 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
}
rcu_read_unlock();
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cs->mems_allowed = parent->mems_allowed;
cs->effective_mems = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
out_unlock:
percpu_up_write(&cpuset_rwsem);
put_online_cpus();
@ -2871,7 +2871,7 @@ static void cpuset_css_free(struct cgroup_subsys_state *css)
static void cpuset_bind(struct cgroup_subsys_state *root_css)
{
percpu_down_write(&cpuset_rwsem);
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
if (is_in_v2_mode()) {
cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
@ -2882,7 +2882,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
top_cpuset.mems_allowed = top_cpuset.effective_mems;
}
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
percpu_up_write(&cpuset_rwsem);
}
@ -2979,12 +2979,12 @@ hotplug_update_tasks_legacy(struct cpuset *cs,
{
bool is_empty;
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, new_cpus);
cpumask_copy(cs->effective_cpus, new_cpus);
cs->mems_allowed = *new_mems;
cs->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
/*
* Don't call update_tasks_cpumask() if the cpuset becomes empty,
@ -3021,10 +3021,10 @@ hotplug_update_tasks(struct cpuset *cs,
if (nodes_empty(*new_mems))
*new_mems = parent_cs(cs)->effective_mems;
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
cpumask_copy(cs->effective_cpus, new_cpus);
cs->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
if (cpus_updated)
update_tasks_cpumask(cs);
@ -3186,7 +3186,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
/* synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
if (!on_dfl)
cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
/*
@ -3206,17 +3206,17 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
}
}
cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
/* we don't mess with cpumasks of tasks in top_cpuset */
}
/* synchronize mems_allowed to N_MEMORY */
if (mems_updated) {
spin_lock_irq(&callback_lock);
raw_spin_lock_irq(&callback_lock);
if (!on_dfl)
top_cpuset.mems_allowed = new_mems;
top_cpuset.effective_mems = new_mems;
spin_unlock_irq(&callback_lock);
raw_spin_unlock_irq(&callback_lock);
update_tasks_nodemask(&top_cpuset);
}
@ -3317,11 +3317,11 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
{
unsigned long flags;
spin_lock_irqsave(&callback_lock, flags);
raw_spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_cpus(task_cs(tsk), pmask);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
raw_spin_unlock_irqrestore(&callback_lock, flags);
}
/**
@ -3382,11 +3382,11 @@ nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
nodemask_t mask;
unsigned long flags;
spin_lock_irqsave(&callback_lock, flags);
raw_spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_mems(task_cs(tsk), &mask);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
raw_spin_unlock_irqrestore(&callback_lock, flags);
return mask;
}
@ -3478,14 +3478,14 @@ bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
return true;
/* Not hardwall and node outside mems_allowed: scan up cpusets */
spin_lock_irqsave(&callback_lock, flags);
raw_spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
cs = nearest_hardwall_ancestor(task_cs(current));
allowed = node_isset(node, cs->mems_allowed);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
raw_spin_unlock_irqrestore(&callback_lock, flags);
return allowed;
}